Update 0.22 is now live.
Turbines
-added turbine Test Run Mode: tweak turbine settings while it's running and see how it affects performance
-added manual compressor stage & turbine pressure ratio setup (Advanced Setup - Simple Setup works like before)
-added Bleed Air resource: turbines can provide bleed air that can be used to start other turbines and more in the future
-increased maximum turbine alternator and hydraulic power
-slightly decreased turbine efficiency (engines made in the previous version may require tuning)
-decreased min and increased max combustor temperature
Rotors
-increased max rotor blade count to 8
-added a rotor blade chord setting
-rotor blades can now break under high G-load and speed
-added vortex ring state, overspeed and load warnings to the in-flight readout
-fixed missing sound on the Tail Rotor
-improved rotor audio looping
Aerodynamics
-increased wing drag just after stall which can make the aircraft yaw and possibly spin
-increased camber effect from leading edge flaps
-decreased ground effect strength
-added wing snap sound effect
-fixed incorrect fuselage center of pressure
-fixed asymmetric vapor effects
New Parts
-added a Ducted Fan
Game Mechanics
-added an Era system which estimates the earliest year your aircraft could have been built (currently implemented for propulsion and fuels)
-added Unit Cost, Part Count and Build Time (time you have spent on making the plane) to the craft Specifications window
Craft Inputs
-fixed some bugs affecting the Switch type input
Weather and Effects
-added new weather effects: it gets dark and foggy below thick clouds (requires Advanced Sky, Volumetric Clouds and Fog settings to be enabled)
-improved volumetric cloud performance
-increased vertical wind strength as the air moves over mountains
-added contrails for turbines and ramjets
Other
-top and bottom RCS no longer affect stealth rating
-added hardpoint ejection force parameter
-adjusted ramjet performance
-fixed landing gear root hinge drag problem
-added editor directional light toggle